In the measurement of biophysiological data, for example, in electrocardiography, it is common to use electrodes attached to a patient to obtain signals which indicate physiological conditions and functions. The electrical signals present on the electrodes may be combined in various ways, that is "lead formation," resulting in signals called "leads."
Different systems of lead formation for electrocardiography have been developed, such as Einthoven, Frank and Cabrera, and are well known in the art. Systems have been developed for use in pediatrics, and all of these systems may be subdivided according to number of leads. Each of these different systems of lead formation present a heart's electrical signals in a different form, and in effect, provide a different view of the patient's heart.
Previously, resistor networks have been used to perform the lead formation. Such a hardware solution resulted in relative inflexibility in the lead combinations available. New or experimental lead combinations could not be used without altering the hardware. Furthermore, the precision and accuracy of lead combinations done by resistor networks are limited to the precision and accuracy of the resistors.